The Museums Lockheed Martin X is the prototype for the new F It was originally the XA and was modified to include the liftfan engine for testing of the STOVL concept Among its many test records this aircraft was the first in history to achieve a short takeoff level supersonic dash and vertical landing in a single flight It is also the first aircraft to fly using a shaftdriven liftfan propulsion system The XB flight test program was one of the shortest most effective in history lasting from June to August This photo is the afterburner section of the F engine that powers the XB